I got them at 3inches 5months ago and they are the same. I thought the bigger the fish potential the quicker they grow. I have good water and feed them well. Why o why aren't they getting bigger.
What size tank are you keeping them in, what are you feeding them, how often are you feeding them, and what temperature is you aquarium kept at? Mine went from about 2.5-3" to 9"+ in about a year in my 220.
Mine are a few years old, bought them at 1.5-2". From looking into the tank id say they are 6-7". They are real slow growers. Went from a 55gal for a few months, then to a 180 and now 330, so they always had the room... I kinda wanna pick up 2 more, but I think my 13" fish will eat them
Got all mine year and a half ago (I think) at 1.5 inches now my big brute is ~12" and the little guy is 10". 265 gallon tank 80-85 degrees (I let it drift with the seasons slightly) feeding flak, pellets and live worms.
However even in a tank that size they are a bit skittish. So tank size makes a huge difference with them.
They are also the largest fish in the tank and the tank is heavily filtered, well fed and organics are 0,0,0 tested weekly, water change 1-2 times per week reconstituted RO.
When I had them, about 2.5-3yrs ago, I bought them at about 4" kept them for about 6 months, at which point they were 6-7". I was not knowledgeable about fish back then and they were in only a 39 tall, with cichlids and...2 PACU!, and did water changes very rarely, mostly topped off! Eating a diet of cichlid pellets. Not sure how they thrived in such a bad environment.